#2 Kalidou Koulibaly (Napoli)

Koulibaly has established himself as one of Europe's finest centre-backs after some impressive seasons at Napoli. He was a key member as his side almost pipped Juventus to the league title only to fall short at the end.
The Senegalese excelled in coach Maurizio Sarri's possession-based system and he can carry that to the Emirates where those qualities will be appreciated. His pace, strength, and composure on the ball have many clubs circling and Arsenal would love to beat them to him.
Arsenal have longed for a stable partner alongside stalwart Laurent Koscielny over the years and they would get that in Koulibaly. Furthermore, Koscielny is currently injured which makes the need to sign an experienced centre-back all the more crucial.